[Gumstix-users] Verdex, I2C, GPIO, mA, V, limits

Hi,
It's my understanding that the specific mA/V limits on the GPIO pins
(say for Verdex GX motherboards/breakout board) are going to be based on
the voltage the board is operating on. The PXA270 specs list anything
from 1.8 to 3.3 V as options, but I haven't been able to find any solid
reference to what is actually implemented on the Verdex
motherboard--just hints at 3V...
Full disclosure: I'm looking at getting data from a ADC (MAX1236/1237,
maybe) that outputs serial data, probably using the I2C bus from the
breakout-vx. I believe the limits for I2C and GPIO are the same, but
both are interesting to me in any case.
Thanks for any thoughts/help.
Krzysztof

Thread view

Hi,
It's my understanding that the specific mA/V limits on the GPIO pins
(say for Verdex GX motherboards/breakout board) are going to be based on
the voltage the board is operating on. The PXA270 specs list anything
from 1.8 to 3.3 V as options, but I haven't been able to find any solid
reference to what is actually implemented on the Verdex
motherboard--just hints at 3V...
Full disclosure: I'm looking at getting data from a ADC (MAX1236/1237,
maybe) that outputs serial data, probably using the I2C bus from the
breakout-vx. I believe the limits for I2C and GPIO are the same, but
both are interesting to me in any case.
Thanks for any thoughts/help.
Krzysztof

Hi Krzysztof,
> It's my understanding that the specific mA/V limits on the GPIO pins
> (say for Verdex GX motherboards/breakout board) are going to be based on
> the voltage the board is operating on. The PXA270 specs list anything
> from 1.8 to 3.3 V as options, but I haven't been able to find any solid
> reference to what is actually implemented on the Verdex
> motherboard--just hints at 3V...
I'm pretty sure that the verdex runs at 3.3v. You should be able to
measure the voltage from any of the GPIO pins when they're being
driven high.
> Full disclosure: I'm looking at getting data from a ADC (MAX1236/1237,
> maybe) that outputs serial data, probably using the I2C bus from the
> breakout-vx. I believe the limits for I2C and GPIO are the same, but
> both are interesting to me in any case.
With i2c, the processor only drives the pins to ground. For a high,
the pin floats, and the pullup resistors pull the voltage up. Don't
pullup to any higher than 3.3v.
--
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/

Community

Help

Get latest updates about Open Source Projects, Conferences and News.

Sign up for the SourceForge newsletter:

I agree to receive quotes, newsletters and other information from sourceforge.net and its partners regarding IT services and products. I understand that I can withdraw my consent at any time. Please refer to our Privacy Policy or Contact Us for more details